One of best mathematics book for game programming is Mathematics for 3D Game Programming and Computer Graphics, Third Edition. It will show you the basic mathematics which is used not only Unreal Engine but all the 3D game engine.
Thank you. I have this book on my desk My question was related to UE4. I have a hard time explaining things to freelancers and third-party developers. A concise explanation would be great - with Unreal Engine terminology, screenshots, examples.